Earlier in the day, Biden called Russian President Vladimir Putin a "crazy SOB" during his presidential campaign tour.
"Rude," the president said, when reacting to Biden’s statement.
Putin mentioned his previous statement where he said that Biden is more preferable US president for Russia than former US President Donald Trump
"And judging by what he just said, I’m absolutely right, because this is an adequate reaction to what I said," Putin said, adding that Biden "can not just say thank you."